In that recent shark attack off the coast of Los Angeles caught the attention of millions of Americans heading to the beach this summer. But sharks aren't the only danger lurking in the water. The water itself is a growing hazard. Here's ABC's David Wright. Watch out! Reporter: This frantic scene on the southern California coast, a swimmer unable to climb out of the churning water, is becoming far too common. Hold on, hold on. Since July 1st, we had 50 rescues in this particular area. That's only a half mile stretch of coastline. Reporter: 50 rescues? 50 rescues. Reporter: Across L.A. County, coastal rescues are up 300% over last year. The problem? Warm, hot weather means a lot more swimmers in the water. Plus, teenagers are sharing videos like these on social media, luring others to some of the most treacherous hidden coves along the coast. The scenery couldn't be prettier and the water's an inviting 75 degrees. But a wave like that churns like a washing machine. And if you do happen to get caught in the spin cycle, paradise can suddenly become lethal. You can get physically injured and you can also, you know, get taken under by the water. Reporter: Just this past week, a swimmer drowned here. Lifeguards still haven't recovered the body. So, they are warning everyone. To try and avoid more scenes like this. David Wright, ABC news, palos verdes, California.

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